Performance comparison of three commercial tests for the detection of SARS-CoV-2 antibodies in a common set of pediatric samples.

BACKGROUND: Serologic testing for SARS CoV-2 is useful for detection of past infection and assisting in diagnosis of post-COVID-19 syndromes such as MIS-C. Immune responses to SARS-CoV-2 infection in children differ from adults but most antibody performance studies are limited to adults. OBJECTIVE: The objective of this study was to compare three commercial SARS-CoV-2 antibody kits in a common set of children being evaluated for SARS-CoV-2 infection. METHODS: Three SARS-CoV-2 antibody tests: Abbott anti-nucleocapsid (N) IgG (AA), Epitope Diagnostics anti-N IgG (EDI) and EUROIMMUN anti-S1 Spike IgG (EU) were compared against two references: 1) RT-PCR and 2) consensus IgG (consIgG). RESULTS: All three tests had a sensitivity <53% compared to RT-PCR, with EU outperforming EDI (p = 0.03). When all samples were compared to consIgG, positive percent agreement was comparable (AA-90%, EU- 98% and EDI- 88%) but EDI had significantly better negative percent agreement than EU (p = 0.009). No difference in test performance was observed using either reference when samples were collected ≥15 days post-symptom onset (PSO). CONCLUSIONS: Our findings suggest good performance of commercial SARS-CoV-2 IgG assays in pediatric patients with samples collected ≥15 days PSO. Additional studies investigating antibody response and assay performance in children are warranted.